BACKGROUND: Electrocardiographic changes are well known to appear with acute cerebrovascular events. OBJECTIVE: To investigate if QT dispersion (QTd) is increased in patients who have an acute stroke and if this increase could be related to lesion extent and/or localization. DESIGN: The study group consisted of 36 patients who had an acute stroke and no history or signs of cardiovascular disease. An age-matched control group (n = 19) free of cardiovascular disease was also included. Simultaneous 12-lead electrocardiograms (ECGs) were recorded within the first 24 hours (24h-ECG) and after 72 hours (72h-ECG) from stroke onset. QT dispersion was assessed both manually and automatically with assessors blinded to the clinical data. RESULTS: QT dispersion, corrected QTd, and automated QTd were significantly increased in the 24h-ECG compared with the 72h-ECG (60 [range, 20-80] milliseconds vs 40 [range, 0-80] milliseconds, P<.005; mean [SD], 56 [19] vs 36 [21] milliseconds, P<.001; and 50 [range, 14-94] vs 34 [range, 0-84] milliseconds, P<.005, respectively). However, QTd in the 72h-ECG was similar to QTd in the control group. While in the 24h-ECG corrected QTd was significantly greater in patients with large infarcts and large hemorrhages (mean [SD], 70 [20] vs 51 [20] milliseconds, P<.05), in the 72h-ECG corrected QTd was greater in patients with right vs left-sided lesions (mean [SD], 39 [18] vs 24 [18] milliseconds, P<.05). CONCLUSIONS: QT dispersion is increased in the first 24 hours in patients with acute stroke and no cardiovascular disease compared with the control group. Although this finding seems to be related to the size of the lesion rather than to the localization or type of stroke, after 72 hours specific lesion localization could also influence the QTd.